A variety of intruder detection systems are currently available. In some intruder detection systems, known as "pinpoint" systems, a plurality of detection boxes ("pinpoints") are spaced along a fence or other element to be monitored. Each pair of adjacent detection boxes is intended to monitor the area between them. These systems are relatively cumbersome and expensive and are not unobtrusive since the detection boxes are clearly visible.
One such system is marketed by R. B. Tec, Ltd., P. 0. B. 47117, Ramat Hasharon, Israel.
A more desirable category of intruder detection systems is the category of mechanical disturbance detecting cable systems in which the intruder detection function is performed by a sensing cable disposed along the fence or element to be monitored. The sensing cable typically engages the fence at a plurality of locations.
The sensing cable in these systems typically includes a piezo-electric or magnetic or microphonic cable which is operative to generate an electric signal in response to mechanical disturbances within a sensing radius characterizing the sensing cable. This electrical signal serves as a warning of the presence of an intruder.